Collaborative communication-based ocean observation research with heterogeneous unmanned surface vessels

With the development of technologies related to unmanned vehicles, including unmanned aerial vehicle and unmanned surface vehicle, unmanned vehicles play a pivotal role in maritime management and cruise activities. Meanwhile, lots of evidence shows that a single unmanned vehicle is not qualified for operation under complex environment, whereas the unmanned aerial vehicle–unmanned surface vehicle formation consists of multiple unmanned aerial vehicles and unmanned surface vehicles, which can enhance the performance of the single unmanned vehicle significantly. However, the cooperative operation performance of the unmanned aerial vehicle–unmanned surface vehicle formation is constrained by its communication capacity. Consequently, a cooperative communication framework is designed for the unmanned aerial vehicle–unmanned surface vehicle formation. A distributed dynamic network topology is constructed for fulfilling effective communication for the unmanned aerial vehicle–unmanned surface vehicle formation based on ad hoc network. Experiments are carried out by employing the built unmanned aerial vehicle–unmanned surface vehicle formation platform. Results verify the superiority of the designed cooperative communication framework for the unmanned aerial vehicle–unmanned surface vehicle formation.

Unmanned Surface Vehicle (USV) is vessel that can move without human to control. USV is capable of moving using the thrust force and can maneuver using the deflection angle of rudder. USV has a 6-degree of freedom which are non-linear system that can be approached with the 3-degrees of freedom. The purpose of dynamic modeling of USV is to achieve the models and parameters of real USV. Non-linear least square Levenberg-Marquardt method can be applied to estimate USV model as a non-linear system. The purpose of controlling USV is to set the surge velocity and the yaw-rate so that the USV movement can be controlled. Proportional integral controller can be used to manipulate the velocity and to accelerate the response speed of the USV’s velocity. Parameters validation results show that the dynamic modeling methods could generate the parameters nearly equal to the true parameters. This is evidenced by the relatively small RMSE value in x-axis acceleration, y-axis acceleration, and yaw-axis acceleration. The result of controller testing illustrate that the designed controller can adjust the surge velocity and yaw-rate and fit the time constant controller design specification. Further, the testing show that the responses have zero steady state errors.

This paper presents a dynamic model estimation using system identification (SI) technique and a multivariable controller design for an unmanned surface vehicle (USV) with two fixed thrusters. The catamaran shaped USV has been developed for marine research and surveying exploration in costal area. To validate the automatic control performance of USV, which is designed by classical PID controller, we carried out experiments to keep the USV's position at a fixed point and to track predefined positions. As a result, we have found that it needs time-consuming efforts to tuning the weight between heading and speed controller since the yawing and surge motions are tightly coupled to the two thrusters. In order to solve the problem, it is necessary to introduce the multivariable controller design method. And a numerical dynamic model is required for the model based design. This paper addresses the estimation of a dynamic model of the USV based on the experimental results and the design of Linear-Quadratic (LQ) controller based on a multivariable control method. To verify the efficiency of the designed controller using the estimated dynamic model, numerical simulations were carried out.

Autonomous Underwater Vehicle (AUV) has played an increasingly important role in seafloor exploration, marine landscape observation and marine military field in recent years. Because the AUV’s endurance and communication capability are very limited, the AUV need to be regularly recycled for energy replenishment and data transmission. As a small unmanned surface platform, Unmanned Surface Vehicle (USV) whose technical development has been relatively mature can able to connect underwater unmanned platform with floating unmanned platform. Therefore, the study of the interrelationship between AUV and USV is full of prospects and challenges. In order to establish the connection between USV and AUV to further achieve the purpose of USV recycling AUV, this paper designs a new type of towing device with attitude measurement and attitude adjustment based on the existing towing technology and the Bernoulli equation. And the device is introduced from the aspects of mechanical design, force analysis and motion simulation. Through numerical simulation, it is found that the stabilizing wing can provide downward pressure for the towing device and the tail rudder can provide the diving moment for the towing device, which can ensure the depth stability of the towing device. The attitude of the towing device can be adjusted in real time by adjusting the angle of the tail rudder. In conclusion, this way takes an important step towards the wider practical application of AUV.

Unmanned surface vehicle (USV) formation is a hot topic of current research. Path planning is the core technology for USV formation. This paper focuses on a USV formation path planning problem considering kinetic constraints. Firstly, an improved A* algorithm is proposed to solve the point-to-point path planning of a USV considering kinetic constraints. In this algorithm, the yaw constraint is introduced on top of the position constraint to extend the state space of the USV to three dimensions, and the convergence speed is accelerated by building a heuristic map. The dynamics model of the USV is used to generate the minimum trajectory elements to ensure that the path conforms to the kinetic constraints. Secondly, the mathematical model of USV formation based on the virtual structure method is established, and the path planning scheme of formation navigation and formation reconfiguration is given according to the improved A* algorithm. Finally, we carry out a USV model identification experiment for SL900 USV and simulation experiments based on the model. The experimental results show that the output path of the proposed method is smoother compared with the traditional method. This method can provide a globally safe path with kinetic constraints for USV formation navigation and formation reconstruction.

An Unmanned Surface Vessel (USV) deploying a Remotely Operated Vehicle (ROV) has the potential to replace a conventional manned vessel for various operations from field installation to operational support (including inspection, maintenance, repair and drilling support) and decommissioning. The USV deploying ROV (also written as USV+ROV) is already emerging in the oil and gas industry with maturing technology developments and increasing capacities and performance of autonomous vehicles and remotely operated systems. Beyond the safety improvement generated by the absence of personnel onboard the USV, this solution intends to significantly reduce the subsea intervention costs while improving the intervention (planning) flexibility. One of the advantages of the technology is that the operator is located offshore on another vessel or onshore while maintaining a real-time control with the USV+ROV. Threfore, communication link between the operator and the USV+ROV system is critical. To mitigate limitations (latency and bandwidth) of the communication link, an obvious solution is to evolve disruptively towards autonomous system. However, incremental autonomy approach with immediate return on investment could be made possible with careful mission's analysis and thorough analysis of communications limitations on operation efficiency. This paper will present only a methodology that attempts to develop a deep understanding of the communication physical effects and their consequences on performance of targeted remote operations. The impact of latency and bandwidth are studied using interactive simulations associated to future offshore trials. At the time of writing, the simulator has been commissioned and a proof of concept trials has been prepared.

This paper investigates the adaptive fault-tolerant formation control scheme for heterogeneous multi-agent systems consisting of unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs) with actuator faults, parameter uncertainties and external disturbances under directed communication topology. Firstly, the dynamic models of UAVs and USVs are introduced, and a unified heterogeneous multi-agent system model with actuator faults is established. Then, a distributed fault-tolerant formation controller is proposed for the unified model of UAVs and USVs in the plane by using adaptive updating laws and radial basis function neural network. After that, a decentralized formation-tracking controller is designed for the altitude control system of UAVs. Based on the Lyapunov stability theory, it can be proved that the formation errors and tracking errors are uniformly ultimately bounded which means that the expected time-varying formation is achieved. Finally, a simulation study is given to demonstrate the effectiveness of the proposed scheme.

In response to achieving the United Nations Sustainable Development Goals (SDGs) of Climate Action (#13) and Life Below Water (#14), the promotion of autonomous shipping technologies has advanced from the experimental stage to specific regional implementation, presenting the maritime industry with rapid and significant changes and challenges. In the future era, where autonomous vessels dominate shipping, with automated operation systems taking the lead, how successfully shipping companies harness these new maritime transport modes will critically impact the safety, efficiency, and reliability of future vessel operations. With the emergence and development of autonomous vessels, it is crucial to effectively assess the importance and correlation of key factors influencing shipping companies’ adoption of autonomous ships. This study utilizes the Analytic Hierarchy Process (AHP) and Revised Decision Making and Trial Evaluation Laboratory (RDEMATEL) to survey senior managers in container and bulk shipping from Taiwan, China, Japan, and the European Union. Through a literature review on the benefits, opportunities, costs, and risks brought by autonomous shipping, this study aims to understand the critical factors important to shipping companies in adopting autonomous shipping, as well as the correlation between these influencing factors across different shipping sectors. The research findings indicate that “emergency response capability” is a critical factor influencing overall and bulk shipping in the adoption of autonomous vessels, while “incomplete regulations” are the primary factor influencing container shipping in the adoption of autonomous ships. Regarding the correlation of critical influencing factors, “vessel technology development” is the main influencing factor for overall, container, and bulk shipping; “operational performance enhancement” is the primary affected factor for overall and container shipping; and “enhancing personnel and vessel safety” is the main affected factor for bulk shipping. It is hoped that the results of this study can serve as a guide for shipping companies in understanding the benefits and opportunities to be emphasized when adopting autonomous shipping and assist in developing effective strategies to reduce costs and risks.

This paper focuses on motion analysis of a coupled unmanned surface vehicle (USV)–umbilical cable (UC)–unmanned underwater vehicle (UUV) system to investigate the interaction behavior between the vehicles and the UC in the ocean environment. For this, a new dynamic modeling method for investigating a multi-body dynamics system of this coupling system is employed. Firstly, the structure and hardware composition of the proposed system are presented. The USV and UUV are modeled as rigid-body vehicles, and the flexible UC is discretized using the catenary equation. In order to solve the nonlinear coupled dynamics of the vehicles and flexible UC, the fourth-order Runge–Kutta numerical method is implemented. In modeling the flexible UC dynamics, the shooting method is applied to solve a two-point boundary value problem of the catenary equation. The interaction between the UC and the USV–UUV system is investigated through numerical simulations in the time domain. Through the computer simulation, the behavior of the coupled USV–UC–UUV system is analyzed for three situations which can occur. In particular, variation of the UC forces and moments at the tow points and the configuration of the UC in the water are investigated.

The globally K-exponentially stable path following control of an underactuated autonomous surface vehicle (ASV) is proposed based on the cascaded approach.The dynamics model of the ASV path following errors is derived utilizing the Serret-Frenet coordinate originated at the free path reference point, which creates an added control input, i.e., the change rate of the path parameter, to avoid the singularity problem when adopting the coordinate originating at the orthogonal projection point.The path following reference yaw is designed, and the whole path following model is decomposed into two cascaded sub-models, named the position tracking sub-model and the yaw angle and surge velocity tracking sub-model.The global K-exponential stability of the path following errors is proved using the cascaded system theory with the globally exponentially stable yaw angle and surge velocity tracking controllers.The results of the mathematic simulations and the lake trials of a real ASV demonstrate the performance of the proposed path following control algorithm.

This paper attempts to solve a challenge in online relative optimal path planning of unmanned surface vehicles (USVs) caused by current and wave disturbance in the practical marine environment. The asymptotically optimal rapidly extending random tree (RRT*) method for local path optimisation is improved. Based on that, an online path planning (OPP) scheme is proposed according to the USV's kinematic and dynamic model. The execution efficiency of RRT* is improved by reduction of the sampling space that is used for randomly learning environmental knowledge. A heuristic sampling scheme is proposed based on the proportional navigation guidance (PNG) method that is used to enable the OPP procedure to utilise the reference information of the global path. Meanwhile, PNG is used to guide RRT* in generating feasible paths with a small amount of gentle turns. The dynamic obstacle avoidance problem is also investigated based on the International Regulations for Preventing Collisions at Sea. Case studies demonstrate that the proposed method efficiently plans paths that are relatively easier to execute and lower in fuel expenditure than traditional schemes. The dynamic obstacle avoidance ability of the proposed scheme is also attested.

Unmanned surface vehicles (USVs) are rapidly developing and widely used in various offshore environments. However, due to the complexity of the water surface environment and the uncertainty in using USVs, field experiments are faced with the problems of great difficulty, long working time, and high cost. And the simulation experiments are usually needed before this. Therefore, this paper constructs a virtual ocean environment based on the virtual reality technology and Unity3D engine, and reproduces the working state and motion of USVs under different water conditions through kinematics and dynamics modeling. At the same time, the navigation algorithm can also be tested and verified. Using the platform, two kinds of USVs are tested, and a multi-agent reinforcement learning (MA-DRL) based multi-USV cooperative hunting algorithm is implemented, which further verifies the applicability of the platform.

This paper proposes a resilient cooperative control framework for unmanned surface vehicles (USVs) operating under unknown disturbances, input saturation, and communication link faults. A novel resilient distributed observer is developed to simultaneously reconstruct both the state and system matrix of the leader using only local neighbor information without requiring global knowledge of the leader’s dynamics or communication topology as in existing methods. Furthermore, a disturbance-rejection synchronization controller is designed based on the internal model principle and a saturation-compensating auxiliary system. In contrast to conventional strategies that rely on constant-bound disturbance assumptions and lack explicit saturation compensation, the proposed controller achieves online disturbance cancellation without prior knowledge of disturbance characteristics such as frequency, amplitude, and phase, while explicitly handling input saturation. The proposed control strategy could significantly improve tracking accuracy, robustness, and practicality in marine environments. Theoretical analysis and simulations validate the merits and performance of the proposed approach.

To ensure navigation safety, unmanned surface vehicles (USVs) need to have autonomous collision avoidance capability. A large number of studies on ship collision avoidance are available, and most of these papers assume that the target ships keep straight or follows the International Regulations for Preventing Collisions at Sea (COLREGS). However, in the actual navigation process, the target ship may temporarily turn. Based on the above reasons, this paper proposes a multi-ship collision avoidance decision method for USVs based on the improved velocity obstacle algorithm. In the basic dynamic ship domain model, a collision risk model is constructed to improve the accuracy of the risk assessment between the USV and target ships. The velocity obstacle algorithm is combined with the dynamic ship domain, and the collision avoidance timing and method are judged according to the collision risk. The simulation results show that the decision method can handle the situation that the target ship temporarily turns and has an emergency collision avoidance capability. Compared with the traditional VO algorithm, the collision avoidance time of the method is shorter, and the number of course changes is less.

In this work a novel intelligent and distributed low-cost platform for marine observation is introduced. The observatory consists of an autonomous surface vehicle (ASV) and an autonomous underwater vehicle (AUV). This paper is focusing on potential search strategies for such an observatory. A novel search strategy based on Braitenberg search is introduced and the performance of this strategy is compared with the performance of inertia Levy-flight developed in recent work. Different settings of search algorithms are tested and their performance is evaluated using a computer simulation. It is shown that the combination of an ASV performing a pre-programmed search and an AUV performing inertia Levy-flight outperform a single AUV using inertia Levy flight for approximately 95 % of the chosen SGD positions. Both settings clearly outperform the introduced Braitenberg search.